It is a good idea to periodically update gcc to the latest release,
so that you get all the bug fixes and new features.

1.  Save the old version of the compiler.  The new version might
    be flaky, so you want to be able to back out to the previous
    version easily.

    The sources of the current distribution are kept in
    /sprite/src/cmds/gcc/dist.  Move it to /sprite/src/cmds/gcc/dist-XXX
    where `XXX' is the version number.  Create a new `dist' directory
    to put the new stuff.

    IMPORTANT --> Make sure you also save a copy of the binaries.
    This should include a copy of the frontends, and the backends for
    each machine.  If you lose all working copies, then you cannot
    generate a new compiler!  (However if this should accidently happen,
    you can restore them from a dump tape.)


2.  Get the latest version of gcc.  To do this type

        ftp prep.ai.mit.edu

    When you are prompted for an id  Type `anonymous'.  When
    it asks for a password, you can type anything because it
    will just ignore it.

    Once you are logged in, type

    ftp> cd /u2/emacs
    ftp> ls

    This will list the contents of the directory.  Look for a file
    named something like `gcc-1.36.tar.Z'.  Make sure you get the
    latest version.

    To download, type

    ftp> get gcc-1.36.tar.Z

    Since it is a big file, it will take a while to down load.  This
    is a good opportunity to go eat lunch or something.

    One it is downloaded, type

    ftp> quit

    to disconnect.


3.  Uncompress the tar file.  To do this type

        uncompress gcc-1.36.tar.Z


4.  Un-tar the files by typing:

	tar xvf gcc-1.36.tar


5.  In the file /sprite/src/cmds/gcc/sprite there are a bunch
    of files that have special modifications for sprite.  You
    need to run rlog to find out what has been changed in these
    files and then integrate those changes into the distribution.

    All changed files should be placed in gcc/sprite.  gcc/dist should
    only contain the unadulturated distribution.

    See the end of this file for a list of special modifications of gcc
    for sprite.


6.  Recompile the front end:

        cd /sprite/src/cmds/gcc
	make clean
	make mkmf
	make


7.  Recompile the back ends for each machine type.  You need
    to double check all the symbolic links.  Most of them should
    point to /sprite/src/cmds/gcc/dist, but some of them will point
    to the files in /sprite/src/cmds/gcc/sprite.

	cd /sprite/src/cmds/cc1.68k
	make clean
	make mkmf
	make


8.  Test the compiler to make sure it works.  You can do this by
    using the -B option to specify a different search path to find
    the backends.  For instance

    sun3.md/gcc -B/sprite/src/cmds/cc1.68k/sun3.md foo.c

    will cause the compiler to use the new back end, rather than
    the one in /sprite/lib/gcc/sun3.md.

    One very important test is to make sure the new compiler can
    regenerate itself from scratch.


9.  Send mail to `sprite-users' so that everyone knows the compiler
    is about to change.


10.  Install the new compiler.  Run `make install' in /sprite/src/cmds/gcc
     and in /sprite/src/cmds/cc1.$MACHINE for each machine.


11. Make sure that everything still works.  Try compiling several different
    commands.  Run them to make sure that they still work.  Try compiling,
    and booting a new kernel.



-----------------------------------------------------------------------------

Here is a list of special compiler hacks to customize gcc for Sprite.
This list is probably not up to date, so check in /sprite/src/gcc/sprite
and look at the sources to be sure.

    Front end
    ---------
    The front end uses a file called `specs.h' that has specifications
    for multiple machine types.  To specify a particular machine type,
    use the -m flag.

    The front end invokes the preprocessor with both `sprite' and 
    `unix' predefined.


    Preprocessor
    ------------
    The preprocessor has been modified to search for include files in
    machine dependent directories first.  

    __STDC__ can be undefined, so that lint can use the gnu preprocessor.


    cc1 backend
    -------
    cc1 has been modified to recognize any static variable named `rcsid'.
    If this variable is unused it will not complain.  This is so we can
    use RCS without seeing zillions of warnings.